Noise from the aircraft at the time of taking off and landing is a serious problem in the environment around an airport. The noise that is considered to be a problem includes engine noise emitted from an engine and aerodynamic noise emitted from a high-lift-device (for example, a slat, a flap, etc.) and landing gear.
With regard to the high-lift-device, which is one of the sources of the noise described above, because it is a device for obtaining aerodynamics characteristic required at the time of take-off/landing of an aircraft, its design has focused on the aerodynamics characteristic, whereas a design in consideration of noise reduction has not been incorporated.
Accordingly, in current aircraft, there is no known example in which, for example, a structure that reduces noise emitted from a flap, which is a high-lift-device, is included in the flap.
In the recent years, however, because the noise has become a serious problem as described above, efforts for reducing noise are also being made for a high-lift-device. For example, techniques for reducing noise emitted from a flap, which is a high-lift-device, have been proposed (for example, see Patent Literatures 1 to 3).